U.S. patent application number 17/062910 was filed with the patent office on 2021-04-08 for geopolymer cement.
The applicant listed for this patent is Premier Magnesia, LLC. Invention is credited to John Kirin Gehret, Peyton Pool, SR., Jerry Elliot Rademan, Mark A. Shand.
Application Number | 20210101832 17/062910 |
Document ID | / |
Family ID | 1000005169641 |
Filed Date | 2021-04-08 |
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United States Patent
Application |
20210101832 |
Kind Code |
A1 |
Rademan; Jerry Elliot ; et
al. |
April 8, 2021 |
GEOPOLYMER CEMENT
Abstract
A geopolymer cement and a method of producing the same are
provided. A geopolymer cement binder may be provided including a
geopolymer precursor and magnesium oxide as an alkali activator.
The geopolymer cement binder may be mixed with water using high
shear mixing.
Inventors: |
Rademan; Jerry Elliot;
(Atlanta, GA) ; Shand; Mark A.; (Arden, NC)
; Gehret; John Kirin; (Miami Beach, FL) ; Pool,
SR.; Peyton; (Port St. Lucie, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Premier Magnesia, LLC |
West Conshohocken |
PA |
US |
|
|
Family ID: |
1000005169641 |
Appl. No.: |
17/062910 |
Filed: |
October 5, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62910878 |
Oct 4, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B 40/0231 20130101;
B32B 2607/00 20130101; C04B 2111/00612 20130101; C04B 2111/40
20130101; C04B 18/027 20130101; B32B 13/08 20130101; C04B 22/066
20130101; C04B 38/10 20130101; C04B 38/02 20130101; C04B 40/005
20130101; C04B 2103/10 20130101; C04B 28/006 20130101; C04B
2111/2084 20130101; C04B 20/0048 20130101 |
International
Class: |
C04B 28/00 20060101
C04B028/00; C04B 22/06 20060101 C04B022/06; C04B 18/02 20060101
C04B018/02; C04B 20/00 20060101 C04B020/00; C04B 40/00 20060101
C04B040/00; C04B 40/02 20060101 C04B040/02; C04B 38/10 20060101
C04B038/10; C04B 38/02 20060101 C04B038/02; B32B 13/08 20060101
B32B013/08 |
Claims
1. A method of producing geopolymer cement comprising: providing a
geopolymer cement binder comprising: a geopolymer precursor; and
magnesium oxide as an alkali activator; and mixing the geopolymer
cement binder with water using and high shear mixing.
2. The method according to claim 1, wherein the geopolymer
precursor includes a material containing amorphous silicates of one
or more of calcium, aluminum, and magnesium.
3. The method according to claim 2, wherein the geopolymer
precursor includes one or more of: slag cements; fly ash;
metakaolin; fumed silica; and rice husks.
4. The method according to claim 1, wherein the geopolymer cement
binder includes between about 10% to about 95% of the geopolymer
precursor by weight of the geopolymer cement binder.
5. The method according to claim 1, wherein the magnesium oxide
includes magnesium oxide calcined to exhibit a caustic magnesia
activity neutralization time of between about 9 seconds to about 30
seconds using a 1.0N acetic acid.
6. The method according to claim 1, wherein the magnesium oxide
exhibits a magnesium oxide purity from between about 75% to about
99%.
7. The method according to claim 1, wherein the geopolymer cement
binder includes between about 1% to about 50% magnesium oxide by
weight of the geopolymer cement binder.
8. The method according to claim 1, wherein the geopolymer cement
binder further includes a co-alkali activator.
9. The method according to claim 8, wherein the co-alkali activator
includes one or more of: sodium silicate having a formula
Na.sub.2SiO.sub.3.nH.sub.2O, where n=one of 5, 6, 8, 9; potassium
silicate; sodium metasilicate; sodium hydroxide; sodium aluminate;
sodium carbonate; hydrated lime; quick lime; dolime; hydrated
dolime; potassium oxide; lithium oxide; alumina; iron oxide; nickel
oxide; copper oxide; sodium lactate; ordinary Portland cement; and
calcium gluconate
10. The method according to claim 8, wherein the geopolymer cement
binder includes an amount of co-alkali activator that is equal to
or less than an amount of the magnesium oxide by weight.
11. The method according to claim 1, further including carbonating
the geopolymer cement one of during mixing and after mixing.
12. The method according to claim 11, wherein carbonating the
geopolymer cement includes one or more of: adding carbon dioxide to
one or more of the water and the geopolymer cement; providing the
geopolymer cement binder further including a powdered carbonate
including one or more of sodium carbonate, lithium carbonate,
sodium bicarbonate, sodium percarbonate, and sodium
sesquicarbonate.
13. The method according to claim 1, further comprising providing a
density reduction of the geopolymer cement.
14. The method according to claim 13, wherein providing the density
reduction of the geopolymer cement includes one or more of:
aerating the geopolymer cement; and incorporating a density
reduction additive with one or more of the geopolymer cement binder
and the geopolymer cement.
15. The method according to claim 14, wherein aerating the
geopolymer cement includes one or more of: physically aerating the
geopolymer cement; chemically aerating the geopolymer cement using
one or more of a chemical aeration agent and a foaming agent.
16. The method according to claim 14, wherein the density reduction
additive includes a lightweight material, including one or more of:
expanded polymers, expanded polystyrene, perlite, vermiculite,
hollowed glass beads, crushed glass, zeolites, and mica.
17. The method according to claim 1, wherein the geopolymer cement
binder further includes one or more of a ceramic material and a
heat expandable material providing one or more of heat resistance
and thermal shock resistance for the geopolymer cement.
18. The method according to claim 1, further comprising reinforcing
the geopolymer cement including one or more of: providing the
geopolymer cement binder further including one or more of chopped
organic fibers, chopped inorganic fibers including one or more of
fiberglass fibers, basalt fibers, polyolefin fibers, stainless
steel fibers, and nylon fibers; providing one of a woven and a
non-woven mat facing for the geopolymer cement; and providing one
of a woven and a non-woven internal reinforcement.
19. The method according to claim 1, wherein the geopolymer cement
binder further includes a viscosity control agent, including one or
more of: a viscosity reducer; and a thickener.
20. The method according to claim 1, wherein the geopolymer cement
binder further includes an alkali stabilizing activator to increase
the pH of the geopolymer cement.
21. The method according to claim 1, wherein mixing the geopolymer
cement binder with water using high shear mixing includes one or
more of: mixing with an overhead-type mixer having a toothed
dispersion blade; mixing with a rotor-stator high shear in line
mixer; mixing with a pin mixer; and mixing with a multi-stage
cylinder mixer.
22. The method according to claim 1, further comprising shaping the
geopolymer cement, in an uncured state, into a sheet.
23. The method according to claim 22, further comprising one of:
facing at least one surface of the sheet with a facing material;
and one or more of applying a reinforcing layer to at least one
surface of the sheet, at least partially embedding the reinforcing
layer into at least one surface of the sheet, and fully embedding
the reinforcing layer into the sheet.
24. A construction panel comprising: a geopolymer cement sheet
comprising a geopolymer precursor reacted with a magnesium oxide
alkali activator and water under high shear mixing; and one of a
facing material and a reinforcing layer bonded to a surface of the
geopolymer cement sheet.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. provisional
patent application Ser. No. 62/910,878, entitled "Lightweight
Magnesium Oxide-Based Geopolymer Cements" and filed on Oct. 4,
2019, the entire contents of which is incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present disclosure generally relates to geopolymer
cements, and more particularly relates to geopolymer cements
utilizing magnesium oxide as an alkali activator.
BACKGROUND
[0003] Currently the construction board market is generally
dominated by gypsum-based core materials. For example, most
residential and commercial building structures typically utilize
wall, floor and/or ceiling panels having gypsum-based core boards.
While gypsum-based products may provide some degree of fire
resistance, they may often exhibit limited fire resistant
properties when used in the thicknesses now specified in many
current building codes when used in various fire-barrier
assemblies. For example, typically 5/8'' thick Type C and Type X
gypsum boards are only able to provide 1-hour fire rating in the
industry accepted ASTM E119 fire wall assembly test. Although
various fire resistant additives, such as vermiculite, can be
incorporated into the gypsum core building panels, the inherent
ability of the gypsum cores to slow down smoke and fire spread has
limits. Additionally, gypsum core boards are often not especially
strong on their own, and actually develop up to a significant
portion of their flexural and compressive strengths from either a
paper-based encapsulating protective sheathing, or in some cases, a
fiberglass matting material. Unfortunately, a paper sheathing is
also flammable and may be weakened by water and/or moisture
intrusion, which can also lead to dangerous mold and/or mildew
formation, in some situations, as well as weakening on and within
the gypsum cores, which may give rise to the need to replace the
gypsum-based boards. Despite some of these potential issues,
gypsum-based boards have gained widespread use over the years
because these boards are easy for drywall contractors to handle and
apply based on relatively lightweights, easy score & snap
properties, fastener ability properties, are easy to make smooth
and assembled with joint compounds and are relatively
inexpensive.
SUMMARY
[0004] According to an implementation a method of producing
geopolymer cement may include providing a geopolymer cement binder.
The geopolymer cement binder may include a geopolymer precursor,
magnesium oxide as an alkali activator. The method may further
include mixing the geopolymer cement binder with water using high
shear mixing.
[0005] One or more of the following features may be included. The
geopolymer precursor may include a material containing amorphous
silicates of one or more of calcium, aluminum, and magnesium. The
geopolymer precursor may include one or more of: slag cements; fly
ash; metakaolin; fumed silica; and rice husks. The geopolymer
cement binder may include between about 10% to about 95% of the
geopolymer precursor by weight of the geopolymer cement binder.
[0006] The magnesium oxide may include magnesium oxide calcined to
exhibit a caustic magnesia activity neutralization time of between
about 9 seconds to about 30 seconds using a 1.0N acetic acid. The
magnesium oxide may exhibit a magnesium oxide purity from between
about 75% to about 99%. The geopolymer cement binder may include
between about 1% to about 50% magnesium oxide by weight of the
geopolymer cement binder.
[0007] The geopolymer cement binder may further include a co-alkali
activator. The co-alkali activator may include one or more of:
sodium silicate; potassium silicate; sodium metasilicate having a
formula Na.sub.2SiO.sub.3.nH.sub.2O, where n=one of 5, 6, 8, 9;
sodium hydroxide; sodium aluminate; sodium carbonate; hydrated
lime; quick lime; dolime; hydrated dolime; potassium oxide; lithium
oxide; alumina; iron oxide; nickel oxide; copper oxide; sodium
lactate; ordinary Portland cement; and calcium gluconate. The
geopolymer cement binder may include an amount of co-alkali
activator that is equal to or less than an amount of the magnesium
oxide by weight.
[0008] The method may further include carbonating the geopolymer
cement one of during mixing and after mixing. Carbonating the
geopolymer cement may include adding carbon dioxide to one or more
of the water and the geopolymer cement. Carbonating the geopolymer
cement may include providing the geopolymer cement binder further
including a powdered carbonate. The powdered carbonate may include
one or more of sodium carbonate, lithium carbonate, sodium
bicarbonate, sodium percarbonate, sodium sesquicarbonate, potassium
carbonate, and potassium bicarbonate.
[0009] The method may further include providing a density reduction
of the geopolymer cement. Providing the density reduction of the
geopolymer cement may include aerating the geopolymer cement.
Aerating the geopolymer cement may include physically aerating the
geopolymer cement. Aerating the geopolymer cement may include
chemically aerating the geopolymer cement using one or more of a
chemical aeration agent and a foaming agent. Providing the density
reduction of the geopolymer cement may include incorporating a
density reduction additive with one or more of the geopolymer
cement binder and the geopolymer cement. The density reduction
additive may include a lightweight material, including one or more
of expanded polymers, expanded polystyrene, perlite, vermiculite,
hollowed glass beads, crushed glass, zeolites, and mica.
[0010] The geopolymer cement binder may further include one or more
of a ceramic material and a heat expandable material. The ceramic
material and/or the heat expandable material may provide one or
more of heat resistance and thermal shock resistance for the
geopolymer cement, including, but not limited to, cordierite,
mullite, steatite, magnesia stabilized zirconia, ceria stabilized
zirconia, olivine & unexpanded perlite. The method may further
include reinforcing the geopolymer cement. Reinforcing the
geopolymer cement may include providing the geopolymer cement
binder further including chopped fibers including one or more of
fiberglass, basalt fibers, polyolefin fibers, hemp fibers,
stainless steel fibers, and nylon fibers. Reinforcing the
geopolymer cement may include providing one of a woven and a
non-woven facing for the geopolymer cement. Reinforcing the
geopolymer cement may include providing one of a woven and a
non-woven internal reinforcement.
[0011] The geopolymer cement binder may further include a viscosity
control agent. The viscosity control agent may include a viscosity
reducer. The viscosity control agent may include a thickener. The
geopolymer cement binder may further include an alkali stabilizing
activator to increase the pH of the geopolymer cement.
[0012] Mixing the geopolymer cement binder with water high shear
mixing may include mixing with an overhead-type mixer having a
toothed dispersion blade. Mixing the geopolymer cement binder with
water using one or more of high speed mixing and high shear mixing
may include mixing with a rotor-stator high shear in line
mixer.
[0013] The method may further include shaping the geopolymer
cement, in an uncured state, into a sheet. The method may further
include facing at least one surface of the sheet with a facing
material. The method may further include applying a reinforcing
layer to at least one surface of the sheet.
[0014] According to another implementation, a construction panel
may include a geopolymer cement sheet comprising a geopolymer
precursor reacted with a magnesium oxide alkali activator and water
under one or more of high-speed mixing and high shear mixing. The
construction panel may further include one of a facing material and
a reinforcing layer bonded to a surface of the geopolymer cement
sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is an x-ray diffraction plot of an example geopolymer
cement consistent with an illustrative example embodiment;
[0016] FIG. 2 is an x-ray diffraction plot of another example
geopolymer cement consistent with an illustrative example
embodiment; and
[0017] FIG. 3 diagrammatically depicts an illustrative example
conveyer extrusion process, consistent with an illustrative example
embodiment.
DESCRIPTION OF EXAMPLE EMBODIMENTS
[0018] In general, the present disclosure relates to magnesium
oxide based geopolymer cements. For example, geopolymer precursors
which may be reacted with magnesium oxide and water to form
geopolymer cements. In some situations, magnesium oxide having
particular grades and/or reactivities may be mixed with geopolymer
precursors and water under specific mixing conditions to form
geopolymer cements. In some implementations, the resultant
geopolymer cements may, for example, exhibit some degree of heat
and/or fire resistance. In some implementations, the resultant
geopolymer cements may be utilized in connection with construction
products, such as interior and/or exterior wall panel products
(e.g., including, but not limited to, wall panels as may be
attached to construction framing to form an interior or exterior
surface of a wall, ceiling, or the like, and may be used in similar
applications as wallboard and/or drywall), construction panels,
fire-separation wall assemblies, shaft-liner assemblies and/or
various other construction products. It will be further appreciated
from the following description that geopolymer cements consistent
with the present disclosure may be utilized in a wide variety of
other applications.
[0019] As generally discussed above, in some illustrative example
embodiments, a geopolymer cement may generally be produced by
mixing a geopolymer cement binder, or binder system, with water.
Consistent with some embodiments, the geopolymer cement binder may
include at least a geopolymer precursor and magnesium oxide as an
alkali activator. The geopolymer cement binder may be mixed with
the water using high speed mixing techniques and/or high shear
mixing techniques. In some implementations, the geopolymer cement
binder may include various additional ingredients and/or
components. In implementations in which the geopolymer cement
binder may include additional ingredients and/or components, the
additional ingredients and/or components may alter one or more
chemical and/or mechanical characteristics of the resultant
geopolymer cement.
[0020] Consistent with some illustrative examples of the present
disclosure, the geopolymer cement may set at ambient temperatures.
That is, the geopolymer cement may not require heating of the
mixture to produce setting, or hardening, of the geopolymer cement.
Consistent with some implementations, the geopolymer cements may
utilize minimally processed natural materials or industrial
byproducts, which may allow carbon footprint reductions (e.g.,
which may include a significant reduction, in some embodiments),
while also being very resistant to many of the durability issues
that can plague conventional concretes (such as concretes formed
utilizing ordinary Portland cements).
[0021] As generally discussed above, consistent with embodiments of
the present disclosure, a geopolymer cement binder may be utilized
that may include a geopolymer precursor. Consistent with some
embodiments, a geopolymer precursor may include an inorganic,
amorphous alkali metal or metal silicate material, such as an
aluminosilicate. Without limitation to particular mechanisms, in
some implementations such geopolymer precursors may react with
alkaline activators that may chemically attack the aluminosilicate
material to release reactive chemical species such as hydrated
ortho-silicate and aluminate anions, as well as Ca.sup.2+,
Al.sup.3+ and Mg.sup.2+ cations. These species may then react and
condense into reaction products, such as C-A-S-H (calcium, aluminum
silicate hydrates) gels like, for example, similar to those seen in
Portland cement. Dependent upon the level of Ca present in the
system, condensation of three-dimensional alkaline polymer, N-A-S-H
(sodium, aluminum, silicate hydrates) gels can occur which can be
regarded as zeolite precursor. It is also possible that a hybrid
polycondensation can occur which results in the formation of a
complex mix of cementitious gels, including C-A-S-H (with the
inclusion of sodium into its composition) and (N, C)-A-S-H (high
calcium content N-A-S-H gels). A phase known as hydrotalcite
(Mg.sub.6Al.sub.2CO.sub.3(OH).sub.16.4H.sub.2O) may also form which
may contribute to early strength and incremental fire resistance of
the cementitious system.
[0022] Consistent with some embodiments, the geopolymer precursor
may include a material containing amorphous silicates of one or
more of calcium, aluminum, and magnesium. Further, consistent with
some embodiments, the geopolymer precursor may include slag cements
(e.g., such as slag cements from blast furnaces, such as ground
granulated blast furnace (GGBF) slag, or other slag generated from
the productions of steel. In some embodiments, the geopolymer
precursor may include fly ash (e.g., including any grade of fly
ash, such as class C or class F). Consistent with some embodiments,
class C fly ash may be beneficial as it may have a higher content
of calcium silicate, which may be useful in forming complexes with
the magnesium in the magnesium oxide to form the
magnesium-calcium-silicate-hydrate crystalline cement phase. In
some embodiments, the geopolymer precursor may include one or more
of metakaolin, fumed silica (microsilica), and rice husks. It will
be appreciated that combinations of geopolymer precursors may be
utilized in connection with embodiments of the present
disclosure.
[0023] Consistent with some embodiments, magnesium activated alkali
geopolymer cement formulations using slag, fly ash, silica fume,
metakaolin, rice husks, or any other known geopolymer cement
precursors that can react with certain grades of magnesium oxide to
form phases of Magnesium Silicate Hydrate (M-S-H), Calcium Silicate
Hydrate (C-S-H), hydrotalcite, calcium-magnesium silicate hydrate,
and calcium-magnesium-aluminum silicate hydrate cement phases, as
well as alkaline aluminosilicate hydrate gel or zeolite precursor,
may be utilized, which may form an effective "refractory type
cement" that may also exhibit water and mold resistance.
[0024] Consistent with the present disclosure, the geopolymer
cement binder may include between about 1% to about 95% of the
geopolymer precursor by weight of the geopolymer cement binder.
Consistent with some illustrative example embodiments, the
geopolymer cement binder may include between about 10% to about 95%
of the geopolymer precursor by weight of the geopolymer cement
binder. In some particular implementations, the geopolymer cement
binder may include between about 45% to about 75% of the geopolymer
precursor by weight of the geopolymer cement binder. In some
illustrative example embodiments, the geopolymer cement binder may
include between about 1% to about 10% of the geopolymer precursor
by weight of the geopolymer cement binder. It will be appreciated
that other ranges of geopolymer precursor may equally be
utilized.
[0025] Consistent with some embodiments of the present disclosure,
magnesium oxide may be utilized as the primary alkali activator for
the geopolymer cement. In some such implementations, the use of
magnesium oxide as the primary alkali activator may avoid and/or
reduce the usage of extremely highly alkali activators (e.g.,
activators having pH higher than the pH of magnesium oxide), such
as sodium hydroxide, sodium meta-silicate, or even hydrated or
unhydrated Lime, etc., which may present storage, safety, and/or
handling concerns. Further, consistent with some implementations,
the proper mixing of magnesium oxide with geopolymer cement
precursors (e.g., such as slag, fly ash, etc.) and water may aid in
the development of desirable cement phases, which may provide
increased fire-resistant properties in the resultant cement.
[0026] Consistent with some embodiments, the magnesium oxide may
include magnesium oxide calcined to exhibit a caustic magnesia
activity neutralization time of between about 9 seconds to about 30
seconds using a 1.0N acetic acid. Further, in some implementations,
the magnesium oxide may exhibit a magnesium oxide purity from
between about 75% to about 99%. In some illustrative example
embodiments, the magnesium oxide may exhibit a magnesium oxide
purity from between about 89% to about 95%. For example, in some
implementations, it has been found that the magnesium oxide
concentration and type may influence the ability of the magnesium
oxide to activate the geopolymer precursors, and/or may influence
the properties of the resultant geopolymer cement. For example, the
magnesium oxide may be from a naturally calcined grade derived from
mined magnesite (MgCO.sub.3), or from synthetic grades precipitated
from magnesium salt brines or other salt waters, or from flash
calcined grades. In some implementations, the highest surface
reactive grades, such as Flash calcined, synthetic grades and other
high surface reactive grade, may provide beneficial results. One
such grade of magnesium oxide may include a relatively highly
reactive natural (e.g., derived from mined Magnesite) grade that
may be calcined in a Herreshoff multi-hearth furnace that exhibit a
caustic magnesia activity neutralization time of between about 9
seconds to about 30 seconds using a 1.0N acetic acid. A product
called MAGOX.RTM. 93HR produced and marketed by Premier Magnesia,
LLC is an example of such a grade. An example of a synthetic highly
reactive grade of magnesium oxide is MagChem 30, 40 or 50 produced
by Martin Marietta, Inc. with activity neutralization times ranging
from 8 seconds to as high as 21 seconds. Flash Calcined magnesium
oxide grades may also be useful, e.g., as they can produce activity
neutralization times ranging from 12 seconds up to 23 seconds or
more.
[0027] Consistent with some experimental embodiments, various
geopolymer cement precursors were tested that contain SiO.sub.2,
Al.sub.2O.sub.3, CaO, Fe.sub.2O.sub.3, (Na.sub.2O and K.sub.2O.
These materials have been known to be "polymerizable" via inorganic
hydration and crystalline phase formation routes. Although they
could often times form superior cements compared to gypsum/stucco
or ordinary Portland cements (OPC), the resultant cements have been
observed to have issues with early strength development, excessive
cracking from overly aggressive high alkalinity activators, such as
sodium meta-silicate, caustic soda (NaOH) or various forms of lime
(CaO). Consistent with the present disclosure, it has been
discovered that the use of a proper grade of magnesium oxide may
overcome and/or mitigate at least some, if not all, of these above
issues. As noted above, consistent with some implementations,
grades of magnesium oxide that have been found to be effective may
include highly reactive grades that are calcined in a Herreshoff
multi-hearth furnace that exhibit a caustic magnesia activity
neutralization time of between about 9 seconds to about 30 seconds
using a 1.0N acetic acid. The use of this type of MgO grade may
provide improved cement properties while suitable and sustainable
alkalinity activation of stated geopolymer cements can be achieved
without causing cracking or strength loss.
[0028] In some situations, magnesium oxide has been observed to act
as a cement shrinkage compensation admixture in Portland-based
concretes by expanding during hydration compensating from OPC's
shrinkage during the same hydration period. Consistent with some
implementations, the use of magnesium oxide as an alkali activator
for the geopolymer precursors may provide the additional benefit of
reducing potential cement shrinkage during the curing process of
the geopolymer cement. It is observed that not all magnesium oxide
may be consumed in the geopolymer reaction, which may allow for
shrinkage reduction or compensating activity. Residual magnesium
oxide may also provide additional environmental benefit of
absorbing atmospheric CO.sub.2, which may help reduce greenhouse
gases, e.g. hydrotalcite formation.
[0029] Consistent with the present disclosure, the geopolymer
cement binder may include between about 1% to about 50% magnesium
oxide by weight of the geopolymer cement binder. Further, in some
particular implementations, the geopolymer cement binder may
include between about 5% to about 25% magnesium oxide by weight of
the geopolymer cement binder.
[0030] Consistent with some implementations of the present
disclosure, the geopolymer cement binder may further include a
co-alkali activator. For example, in some implementations a higher
pH (e.g. as compared the pH of 10-10.5 provided by magnesium oxide
alone) may be beneficial to generate a desired cure time or
crystalline phase, co-alkali activators may be used on combination
with magnesium oxide. Consistent with various example embodiments,
the co-alkali activator may include one or more of: sodium
silicate; potassium silicate; sodium metasilicate having a formula
Na.sub.2SiO.sub.3.nH.sub.2O, where n=one of 5, 6, 8, 9; sodium
hydroxide; sodium aluminate; sodium carbonate; hydrated lime; quick
lime; dolime; hydrated dolime; potassium oxide; lithium oxide;
alumina; iron oxide; nickel oxide; copper oxide; sodium lactate;
ordinary Portland cement (OPC); calcium aluminate, calcium sulfa
aluminate and calcium gluconate. Consistent with some illustrative
example embodiments, OPC, calcium aluminate, and calcium
sulfoaluminate may additionally and/or alternatively act as
co-cements. For example, the OPC, calcium aluminate, and/or calcium
sulfoaluminate (CSA) may form additional and/or alternative cement
domains within the final geopolymer cement.
[0031] Consistent with some embodiments, the geopolymer cement
binder may include an amount of co-alkali activator that is equal
to or less than an amount of the magnesium oxide by weight. For
example, consistent with some experimental embodiments, it has been
observed that beneficial results may be achieved when the magnesium
oxide is used as the dominant reactor/activator for the geopolymer
cement. A phenomenon has been observed when other alkali activators
are used in combination with magnesium oxide (as described in
greater detail below). For one, it has been observed that the
formation of Magnesium Silicate Hydrate (M-S-H) and Magnesium
Aluminate Hydrates and Magnesium-Calcium Silicates and
Magnesium-Calcium Aluminate Hydrates may be significant crystalline
phases that produce the necessary "glue" that may, at least in
part, determine and/or influence the overall compressive and
flexural strengths as well as fire-resistance some implementations
of the geopolymer cements herein. Some suitable geopolymer
precursor materials, such as slag, fly ash, and other, are believed
to include sufficient calcium content to be reacted with magnesium
oxide if they are liberated utilizing the high-speed mixing and/or
high shear mixing (as discussed in greater detail below). However,
it is believed that too much competition from the other
non-magnesium reactants may slow down or even stop the necessary
magnesium oxide reactions from forming the proper cement phases.
Therefore, if too much co-alkali activators such as hydrated
"Slaked" lime (CaOH.sub.2) or unhydrated "quick" lime (CaO),
sodium, potassium, or calcium silicates, or other alkaline
co-reactants are used, the alkaline co-reactants may compete with
the reactivity of the magnesium oxide and potentially weaken the at
least some properties of the resultant geopolymer cements.
Therefore, for example, if any form of lime is used, the usage
rate, individually or in combination with any other co-reactants,
may desirably be kept equal to, or less than, the total
concentration of the magnesium oxide in the geopolymer cement
binder. For example, in one particular experimental example, it was
found that using a 16% level of Quick Lime with 11% of magnesium
oxide caused the cement mix to expand excessively and cause
cracking of the formed cements. It will be appreciated that, in
other implementations, depending upon the co-alkali activator, the
reactivity of the magnesium oxide, the specific geopolymer
precursor, and/or the relative quantities of one or more of the
foregoing in the geopolymer cement binder, and/or other components
which may be include, it may be possible to utilize a co-alkali
activator in an amount greater than the amount of the magnesium
oxide.
[0032] For example, in some embodiments room temperature hardening
of the geopolymer cement may rely on the addition of magnesium and
calcium cations in reaction with similar ions from a geopolymer
precursor (e.g., iron blast furnace slag, or other geopolymer
precursors, as discussed herein). As such, in some implementations,
the potential use of magnesium oxide, in conjunction with Hydrated
Lime (Ca(OH)2) have been found, in certain embodiments, to help
harden certain geopolymer cement formulations. As discussed above,
in some situations, the potential use of any calcium derivative
included at levels above (or in some implementations, equal to) the
included magnesium oxide may interfere with reaction of the
magnesium oxide with the geopolymer precursor. Additionally, in
some experimental observations it has been found that the inclusion
of calcium compounds (e.g., as co-alkali activators) may provide
heat resistance to construction materials below 1,000 degrees F.
However, in some implementations the inclusion of calcium compounds
may provide relatively poor heat stabilizing effects above 1,000
degrees F. Accordingly, the inclusion of calcium compounds (e.g.,
as co-alkali activators), as well as the level of inclusion, may be
application dependent.
[0033] Consistent with some embodiments, the geopolymer cement may
be carbonated one of during mixing and after mixing. For example,
in some experimental embodiments, it was observed that
pre-carbonating a magnesium oxide-geopolymer cement may provide
improved physical and thermally stable magnesium carbonate
crystalline cement phases. In some embodiments, carbonating the
geopolymer cement may include adding carbon dioxide to one or more
of the water and the geopolymer cement. For example, in some
embodiments, carbon dioxide may be bubble through, and/or injected
through, the mix water and/or through the mixed geopolymer mix
prior to setting (e.g., which the geopolymer cement mixture is in a
slurry and/or at least partially fluid state). In some embodiments,
it has been observed that carbonating the geopolymer cement (e.g.,
as through the use of carbon dioxide, as described above) may
provide one or more of pH control (e.g., lowering of the pH),
increased UV stability, water resistance, and/or decreased
permeability, especially at early age, as well, in some
embodiments, provide early age strength development.
[0034] In addition/as an alternative to carbonating the mix water
and/or mixed geopolymer cement using carbon dioxide, carbonating
the geopolymer cement may include providing the geopolymer cement
binder further including a powdered carbonate, such as, but not
limited to, adding various alkali metal carbonates. The powdered
carbonate may include one or more of sodium carbonate, lithium
carbonate, sodium bicarbonate, sodium percarbonate, and sodium
sesquicarbonate. In some implementations, the use of powdered
carbonates (e.g., which may be mixed with the powdered phase of the
magnesium oxide and geopolymer precursor of the geopolymer cement
binder). As generally discussed above, in some embodiments, these
carbonates may provide early aged strength, increased UV stability
and/or incremental water and/or moisture vapor transmission
resistance to the cured magnesium oxide-based geopolymer matrices
of the geopolymer cement.
[0035] Consistent with some embodiments, it may be desirable to
provide a relatively lightweight geopolymer cement (e.g., as
compared with other geopolymer cements consistent with the present
disclosure). Accordingly, in some illustrative example embodiments,
a density reduction may be provided for the geopolymer cement. For
example, in some applications, such as, but not limited to,
interior and/or exterior wall panels or construction panels for
residential or commercial buildings, it may be desirable to
decrease the weight of a given panel. Consistent with some example
embodiments, it may be possible to achieve density reduction of the
geopolymer cements of up to as much as 75%, as compared to
geopolymer cements not including a density reduction. It will be
appreciated that, for example in the context of interior and/or
exterior wall panel products or construction panel products, such a
density reduction may provide multiple advantages, such as reduced
shipping costs, ease of installation, and static loads placed on a
structure utilizing the panels, etc.
[0036] According to various embodiments, providing the density
reduction of the geopolymer cement may include aerating the
geopolymer cement. Aerating the geopolymer cement may include
physically aerating the geopolymer cement. For example, air may be
bubbled through, or injected through, the geopolymer cement (e.g.,
after mixing of the cement, but prior to setting). In some
implementations, the carbonation of the geopolymer cement may also
effectuate a density reduction, e.g., by bubbling or injecting
carbon dioxide through the cement mix. Further, in some
embodiments, aerating the geopolymer cement may include chemically
aerating the geopolymer cement using one or more of a chemical
aeration agent and a foaming agent. For example, in one particular
illustrative example embodiment, pre-carbonating and aerating the
magnesium oxide-based geopolymer cement (e.g., which can, in some
implementation, be utilized for construction materials) may be
accomplished by feeding pressurized carbon dioxide into the cement
during, and/or after, mixing with the pressurized feeding of
products like HYONIC PFM 33 (e.g., which may include an anionic
surfactant produced by GEO Specialty Chemicals, Inc., and/or
another anionic surfactant), proteinaceous surfactants (e.g., such
as Mearlcrete, which may include a protein based surfactant
available from Aerix Industries), and/or any other aerating/foaming
agents applied integrally or by means of injection into the matrix
by use of a foam generator.
[0037] According to some embodiments, providing the density
reduction of the geopolymer cement may include incorporating a
density reduction additive with one or more of the geopolymer
cement binder and the geopolymer cement. According to various
embodiments, the geopolymer cement may include between about 1% to
about 70% density reduction additives by volume of the geopolymer
cement. In some embodiments, the inclusion of the density
reductions additives may reduce the density of the geopolymer
cement by between about 1% to about 60%. The density reduction
additive may include a lightweight material, including one or more
of expanded polymers, expanded polystyrene, perlite, expanded and
unexpanded vermiculite, hollowed glass beads, crushed glass. As
will be appreciated, as used herein, "lightweight" is intended to
include a material having a density that is less than the density
of pure geopolymer cement, such that the inclusion of the
lightweight material results in an overall density reduction of the
geopolymer cement. Consistent with various embodiments, the density
reduction additive may be included with the geopolymer cement
binder and/or may be added to the geopolymer cement during and/or
after mixing (but before setting of the geopolymer cement).
According to some embodiments, the incorporation of the density
reduction additives and/or aeration may still achieve a structure
(such as an interior and/or exterior wall panel product,
construction panel, etc.) having suitable structural
characteristics (e.g., compressive and/or flexural strength), sound
barrier properties, and fire resistance, while realizing a
decreased product weight.
[0038] It will be appreciated that in some illustrative example
embodiments the density reduction agents may generally be alkali
resistant and/or stable. For example, magnesium oxide may generally
have a pH of about 10-10.5. Further, and as generally discussed
herein, in some implementations additional alkaline materials may
be included. As such, in some implementations the density reduction
agents (whether aerating agents and/or lightweight additives) may
be stable and/or resistant to pH ranges up to a pH of 10 and/or up
to higher pH ranges (e.g., pH ranges between 10-14).
[0039] Consistent with some embodiments, the geopolymer cement
binder may further include one or more of a ceramic material and a
heat expandable material. The ceramic material and/or the heat
expandable material may provide one or more of heat resistance and
thermal shock resistance for the geopolymer cement. For example, in
some embodiments, the ceramic materials and/or the heat expandable
materials may provide additional heat resistance and/or thermal
shock resistance by expanding and compensating for any cement
shrinkage on excessive heat cool down conditions. In some
implementations, the materials that may be used for achieving lower
core cement thermal shrinkage may include, but are not limited to,
refractory materials, such as ball clays, with or without
vermiculite. In some implementations utilizing vermiculite the
vermiculite may include a fine, unexpanded grade, e.g., which may
expand upon fire exposure. Additional and/or alternative materials
may include cordierite, mullite, steatite, magnesia stabilized
zirconia, ceria stabilized zirconia, olivine & unexpanded
perlite. It will be appreciated that combinations of the foregoing
materials may be utilized, as well as other materials that may
exhibit similar characteristics and/or properties.
[0040] Consistent with some example embodiments, geopolymer cements
consistent with the present disclosure may demonstrate low and/or
extremely low shrinkage in high temperature exposures. The low
shrinkage may be particularly realized, e.g., when compared to
gypsum-based construction wall boards. In some experimental
embodiments shrinkage as low as 1% of a board material's weight
before fire exposure, e.g., as compared to an average of 5%
observed for gypsum boards of similar thicknesses. In some
implementations, it may be possible to realize even lower shrinkage
(e.g., as may be required for certain applications). In some such
implementations, the addition of refractory materials such as ball
clays with, or without, vermiculite materials may be utilized. For
example, as mentioned above, advantage results may be realized
through the use of ball clays include a fine unexpanded grade of
vermiculite that may upon fire exposure, which may compensate for
thermal shrinkage, especially in a thermal shock situation.
[0041] In some embodiments, the geopolymer cement may be
reinforced. Reinforcing the geopolymer cement may include, for
example, providing the geopolymer cement binder further including
chopped fibers. Example fibers may include one or more of
fiberglass, basalt fibers, polyolefin fibers, stainless steel
fibers, and nylon fibers. Examples of glass fiber types used that
may be integrally dispersed into the geopolymer with MgO cement
binders may include, but are not limited to, glass fibers of
E-glass, A-glass, AR-glass, C-glass, D-glass, ECR-glass, R-glass
and/or S-glass. In the embodiments where higher pH activators are
included (e.g., greater than pH of 10.0), the AR-glass type fiber
may be chosen as it has higher Alkali Resistance (AR). Consistent
with various embodiments, reinforcing fibers may be included at
loading levels of between about 0.5% to about 5% by weight of the
geopolymer cement binder. In some particular embodiments,
reinforcing fibers may be included at loading levels of between 1%
to about 3% of the geopolymer cement binder. Integrating the fibers
into the geopolymer matrix may mechanically reinforce the body of
the geopolymer cement. For example, in an example implementation in
which the geopolymer cement may be used as an interior and/or
exterior wall panel or construction panel, the reinforcing fibers
may increase the flexural strength of the panel. Further, the
reinforcing fibers may aid in keeping the panel in one piece, e.g.,
by bridging any formed cracks during fire or heat exposure.
[0042] In addition/as an alternative to reinforcing fibers mixed
into the geopolymer cement, in some example embodiments reinforcing
the geopolymer cement may include providing one of a woven and a
non-woven facing for the geopolymer cement. For example a woven or
non-woven fabric, scrim, or mesh of any of the foregoing fiber
types may be adhered to an exterior surface of a geopolymer cement
structure and/or fully or at least partially embedded into an
exterior surface of a geopolymer cement structure. For example, in
some embodiments the geopolymer cement may be used to form an
interior and/or exterior wall panel product, or other construction
panel. Consistent with such an implementation, a woven or non-woven
facing may be adhered to one, or both, exterior faces of the
construction panel. For example, in one particular illustrative
example embodiment, a non-woven fiberglass (such as E-glass,
AR-glass, C-glass, D-glass, ECR-glass R-glass or S-glass, etc.) may
be applied to one, or both, faces of a construction panel, for
example, using a urea formaldehyde binder, acrylic coating, or
other suitable bonding means. In some implementations, such a facer
may increase the flexural strength of a construction panel by as
much as 50%. It will be appreciated that various additional and/or
alternative facer materials and structures may be utilized.
[0043] Consistent with some example embodiments, reinforcing the
geopolymer cement may include providing one of a woven and a
non-woven internal reinforcement. For example, a mesh or scrim, or
other reinforcing structure, may be internally disposed within a
geopolymer cement structure. In one particular example embodiment,
in which the geopolymer cement structure may include an interior
and/or exterior wall panel product, or other construction panel,
the panel may be formed with at least one fiberglass mesh
internally disposed within the panel. In some example embodiments,
a construction panel product (such as an interior and/or exterior
wall panel product) may include more than one internal
reinforcement. For example, in particular embodiment an interior
and/or exterior wall panel may be provided including three layers
of internal reinforcement. In one such embodiment, the interior
and/or exterior wall panel may include a reinforcement, such as a
woven or non-woven fiberglass scrim or mesh, which may be generally
centrally disposed within the wall panel. Further a reinforcement,
such as a woven or non-woven fiberglass scrim or mesh, may be
partially and/or fully embedded in the geopolymer cement adjacent
each of the two faces of the wall panel. It will be appreciated
that other variations may equally be utilized. For example, the
panel may be formed in a continuous extrusion process (and/or any
other suitable process). During the extrusion of the panel, the
mesh may be pressed into the panel, such that the geopolymer cement
forms around the mesh prior to hardening. Further, in some
extrusion processes, the mesh may be positioned between two
extruded layers of geopolymer cement, such that the two layers
merge into a single body via the openings in the mesh. Further, in
some implementations, the mesh may be fed through an extrusion
head, such that the extruded geopolymer cement is extruded around
the mesh, thereby integrating the mesh into the extruded panel. It
will be appreciated that a variety of additional and/or alternative
processes may be utilized for integrating a reinforcing structure
(including, but not limited to a mesh) into a geopolymer cement
structure, including a construction panel and/or any other
structure.
[0044] In some implementations, the geopolymer cement binder may
further include a viscosity control agent. Consistent with such
embodiments, viscosity control agents may be utilized to provide
cement viscosities appropriate to production requirements of the
geopolymer cement products being manufactured. Further, in some
embodiments, viscosity control agents may be utilized, at least in
part, to control dispersibility of powdered components (e.g., of
the geopolymer cement binder and/or powdered components that may be
otherwise added to the geopolymer cement), to adjust water
consumption and/or utilization (e.g., as discussed in further
detail below), and/or to adjust the flowability of the mixed
geopolymer cement. Further, in some example embodiments, viscosity
control agents may be utilized to help stabilize an aerated or
chemically induced foam, for example, as may be used, at least in
part, to reduce the density of a geopolymer cement, as discussed
above. For example, in some implementations one or more viscosity
control agents may be utilized to stabilize an aerated or
chemically induced foam during the setting, or hardening, of the
geopolymer cement, which may, at least in part, aid in promoting a
more uniform density and/or void size throughout the geopolymer
cement product. As such, the one or more viscosity control agents
may aid in achieving a geopolymer cement product that may exhibit
more uniform or consistent physical and/or mechanical
properties.
[0045] Consistent with the foregoing, in some implementations the
viscosity control agent may include a viscosity reducer, such as a
superplasticizer. Consistent with some embodiments, examples of
superplasticizers may include, but are not limited to, high or
mid-range water reducers, as discussed in greater detail below.
Further, in some implementations, the viscosity control agent may
include thickeners to increase viscosity. Illustrative example
thickeners, e.g., that may be utilized, at least in part, for
increasing viscosity and mix stability may include thickeners based
on cellulosic gums, fatty acid alcohol or mixtures of fatty acid
alcohols, and in one embodiment, a polysaccharide gum.
Additionally, some embodiments of useful viscosity control agents
may include rhamsan gums, xanthan gums, guar gums, and locust bean
gums.
[0046] Consistent with some embodiments, such viscosity control
agents may utilize high or medium range water reducers, e.g., which
may, in some embodiments, increase the dispersibility of powders in
geopolymer cement slurries, and may also, in some embodiments,
better utilizes the water to help keep water to cement ratios down.
That is, for example, the viscosity control agent may include a
water-reducing admixture, or agent, that may, in some
implementations, reduce the required water content for a concrete
mixture by about 5 to about 10 percent. Consequently, concrete
containing a water-reducing admixture may utilize less water to
reach a required slump than untreated concrete (i.e., concrete not
including a water-reducing admixture). The treated concrete (i.e.,
concrete including a water-reducing admixture) may have a lower
water-cement ratio. In some implementations, this may indicate that
a higher strength concrete can be produced without increasing the
amount of cement. Some recent advancements in admixture technology
have led to the development of mid-range water reducers. Mid-range
water-reducer admixture may water content by at least 8 percent, in
some implementations, and may tend to provide more stable concrete
mixtures over a wider range of temperatures. Mid-range water
reducers may, in some implementations, provide more consistent
setting times than standard water-reducers
[0047] For example, in some implementations, viscosity control
agents may be capable of achieving water to cement ratios as low as
1:4. An illustrative example of such a product is a high range
water reducer (HRWR) called MasterGlenium 7902, produced by BASF
Construction Products Group, which may improve dispersibility of
powders in the geopolymer cement slurry (e.g., during mixing and/or
after mixing, but prior to setting or hardening), may adjust water
consumption and/or utilization and flowability, and/or may aid in
stabilizing a foam (e.g., which may be produced through mechanical
aeration and/or using a chemical foaming agent). Illustrative
examples of high range water reducers that have been identified as
being effective may include, but are not limited to, viscosity
control agents based on polycarboxylic acid derivatives, and/or
naphthalene sulfonates (e.g., such as sulfonated naphthalene
formaldehyde condensate, sulfonated melamine formaldehyde
condensate, acetone formaldehyde condensate and polycarboxylate
ethers). In some particular examples, between about 0.01% to about
2.0% of a high-range water reducer may be utilized, based on the
weight of the geopolymer cement binder, to achieve the desired
effects.
[0048] Consistent with some implementations, the geopolymer cement
binder may further include an alkali stabilizing activator to
increase the pH of the geopolymer cement. In some example
embodiments, the use of alkali stabilizing activators may increase
and maintain the pH of the geopolymer cement mix during the
hardening stage, which may, in some embodiments, improve strength
properties of the resulting geopolymer cement. However, it has been
recognized that in some implementations, the inclusion of some
higher pH activators (e.g., such as NaOH and/or Na meta-silicate)
may tend to "over activate" the geopolymer precursor breakdown, and
may reduce the formation of properly formed cement phases, which
may not be as strong as properly formed cement phases. In some
illustrative example embodiments, the alkali stabilizing activators
may include, but are not limited to, silicon dioxide (SiO.sub.2),
sodium aluminate, aluminum oxide (Al.sub.2O.sub.3), sodium lactate,
calcium lactate, calcium nitrate, calcium nitrite, calcium
gluconate, magnesium lactate, and/or magnesium gluconate.
[0049] As generally discussed above, the geopolymer cement binder
may be mixed with water using one or more of high speed mixing and
high shear mixing. Consistent with some embodiments, the water
content may be between about 15% to about 40% relative to the
geopolymer cement binder. Further, in some particular illustrative
example embodiments, the water content may be between about 20% to
about 30% relative to the geopolymer cement binder. Further, in
some particular illustrative example embodiments, the water content
may be between about 20% to about 35% relative to the geopolymer
cement binder.
[0050] As generally discussed above, mixing the geopolymer cement
binder with water may utilize high shear mixing. Consistent with
the present disclosure, the use of high shear mixing techniques has
unexpectedly been found to allow the magnesium oxide reacted
geopolymer cement matrices to reach high levels of strength, fire
resistance, and mold resistance, which are typically associated
with geopolymer cements that utilize much more chemically
aggressive alkali activators. For example, consistent with some
illustrative example embodiments, the kinetic energy produced by
the high shear mixing may mechanically breakdown the geopolymer
cement precursor particles and/or the magnesium oxide particles.
Breaking down the particles in this manner may create more
reactive, smaller particles and/or may expose the raw materials of
the geopolymer cement. These particles may then exhibit a larger
reactive surface area, which may allow the particles to attach
and/or react with the other ingredients in the geopolymer cement
mix, which may facilitate producing the crystals needed for
geopolymer cements. For example, the desired crystals needed for
producing geopolymer cements may advantageously be formed through
relatively quick interactions of the multiple materials integrating
and/or reacting together at substantially the same time.
Accordingly, contrary to conventional techniques that rely on high
alkali chemicals to breakdown the geopolymer cement precursors,
some embodiments of the present disclosure may utilize mechanical
activation and/or enhancement of the geopolymer cement formation
reactions. As such, consistent with some embodiments, it may be
possible to utilize more user-friendly, lower alkali activators for
the formation geopolymer cements.
[0051] For example, in some illustrative example embodiments, the
strength of the cement may be, at least in part, derived from the
ability for the magnesium oxide to react with the breakdown
products of the geopolymer cement precursors (e.g., such as slag,
fly ash, etc.). For example, in some embodiments, the greater
cement phases may be from the hydrotalcite and M-S-H
(magnesium-silicate-hydrate). That is, in some particular
illustrative example embodiments, it has been observed (e.g., via
x-ray diffraction analysis) that relatively stronger and/or more
fire resistant geopolymer cements may be obtained in cements
including hydrotalcite and M-S-H crystalline phases. As such,
crystalline phases of this variety may be termed "greater cement
phases," and/or desirable cement phases. In some implementations,
the higher shear mixing action may provide greater breakdown of the
geopolymer cement precursors, and may improve the formation of the
desired cement phases. As such, through the use of magnesium oxide
the mixes and processes may be much more user friendly in that the
use of less caustic and less dangerous magnesium oxide activators
may be utilized to promote greater safety, e.g., as compared to the
use of more caustic activators. Consistent with some
implementations, the disclosed magnesium oxide activated geopolymer
cements may utilize not only a chemical alkalizing breakdown of the
geopolymer precursor, but may also utilize a mechanical breakdown
of the magnesium oxide and/or the geopolymer precursor to aid in
releasing the reactive ions, which may react with the specific
highly reactive grades of magnesium oxide particles that may also
be further activated by the high speed and/or high shear mechanical
action.
[0052] Consistent with the foregoing, in some illustrative
embodiments, high shear mixing may provide sufficient mechanical
action to cut into both the magnesium oxide and the geopolymer
precursor, which may make both components more reactive, such that
magnesium oxide, on its own, may be sufficient to be the sole
alkalizing agent and react sufficiently to form the desired
crystalline cement phases.
[0053] Consistent with one illustrative example embodiment, mixing
the geopolymer cement binder with water using high shear mixing may
include mixing with an overhead-type mixer having a toothed
dispersion blade. In one particular illustrative embodiment, an
overhead-type mixer capable of rotation speeds up to about 4500 rpm
may be utilized. For example, in some illustrative example
embodiments mixing speeds may be between about 3,200 rpm to about
6,000 rpm. Further, in some illustrative example embodiments, it
has been found that high shear mixing, e.g., which may utilize a
slower blade mixing, may also provide sufficient shearing to
mechanically breakdown the magnesium oxide and/or the geopolymer
precursor, which may make one or both of the components
sufficiently reactive to produce high quality (e.g., high strength,
high fire resistance, and/or high mold resistance) geopolymer
cement without the use of more caustic alkali activators.
Consistent with some such embodiments, magnesium oxide, on its own,
may be sufficient to be the sole alkalizing agent and react
sufficiently to form the desired crystalline cement phases. In some
particular illustrative example embodiments mixing the geopolymer
cement binder with water using high shear mixing may include mixing
with a rotor-stator high shear in line mixer capable of speeds up
to 4000 rpm. For example, in some illustrative example embodiments,
mixing speeds may be in the range from between about 2,800 rpm to
about 6,000 rpm. It will be appreciated that a variety of
additional and/or alternative high shear mixing techniques may be
utilized to achieve the desired mechanical breakdown of the
geopolymer cement precursors and/or the magnesium oxide, and/or
other components of the geopolymer cement. Illustrative examples of
such mixing techniques may include, but are not limited to, pin
mixers, inline mixers, and multi-stage cylinder mixers, as well as
various additional and/or alternative high shear mixers.
[0054] Consistent with some example embodiments, phosphates may
also be included in the geopolymer cement binder, and/or added to
the geopolymer cement mix (e.g., prior to hardening of the
geopolymer cement). Illustrative example phosphates may include,
but are not limited to, mono-potassium phosphate, sodium mono
hydrogen phosphate, sodium di-hydrogen phosphate, magnesium
mono-hydrogen phosphate, magnesium di-hydrogen phosphate, lithium
mono hydrogen phosphate, lithium di-hydrogen phosphate, and/or
combinations thereof. In some embodiments, the addition of
phosphates may increase water resistance of the resulting cement
and/or may increase the physical properties of the resultant
cement. In some implementations, the further incorporation of
phosphates may create magnesium phosphate cement domains within the
resultant cement.
[0055] In one particular illustrative example embodiment, a
geopolymer cement formulation was prepared include magnesium oxide
at 10% of the geopolymer cement binder weight with 80% by weight of
Class F fly ash, 4% of sodium silicate (and including various
additional additives) and a water-to geopolymer cement binder
content of about 25% was used. This cement mix produced the
crystalline phases, as identified by use of x-ray diffraction,
shown in FIG. 1.
[0056] In another particular illustrative example embodiment, a
geopolymer cement formulation was prepared using 6% magnesium oxide
by weight of the geopolymer cement binder, 90% ground granulated
blast furnace (GGBF) slag by weight of the geopolymer cement
binder, and 4% Sodium Silicate (NaSiO.sub.3) by weight of the
geopolymer cement binder, with a water to geopolymer cement binder
ratio content of about 36%. The x-ray diffraction analysis showed
that the resultant geopolymer cement exhibited the crystalline
cement phases as shown in FIG. 2. During various experimental
trials, the grades of fly ash that were tested included both Class
F and C. Consistent with some particular embodiments, Class C was
found to be beneficial as it has a higher content of calcium
silicate, which may be useful in forming complexes with the
magnesium in the magnesium oxide to form the
magnesium-calcium-silicate-hydrate (Hydrotalcite) crystalline
cement phase. However, Class F fly ash has also been found to
provide useful geopolymer cements.
[0057] As generally discussed herein, geopolymer cements consistent
with the present disclosure may be useful in a wide variety of
applications. In some particular applications, geopolymer cements
may be utilized to produce construction panels, such as interior
and/or exterior wall panel products, as well of various other
construction products. Consistent with one particular
implementation, producing a construction panel may further include
shaping the geopolymer cement, in an uncured state, into a sheet.
For example, in some manufacturing embodiments, the mixed
geopolymer cement may be extruded in a continuous operation, e.g.,
by extruding the geopolymer cement mix onto a conveyor, as
generally shown in FIG. 3. In some embodiments, the method may
further include facing at least one surface of the sheet with a
facing mat material, e.g., such as, but not limited to, a facing
mat material. For example, and as generally described above, in
some implementations a woven and/or non-woven facing may be adhered
to and/or embedded in at least one face of the extruded geopolymer
cement (e.g., either before or after at least partial hardening of
the geopolymer cement and using either an appropriate bonding
agent, and/or mechanical bonding with at least partially unhardened
geopolymer cement). Further, in some embodiments, the method may
further include applying a reinforcing layer to at least one
surface of the sheet, and/or integrating reinforcing materials into
the geopolymer cement. For example, and as also generally described
above, in some embodiments, reinforcing fibers may be mixed with
the geopolymer cement (e.g., included as part of the geopolymer
cement binder, and/or added to the geopolymer cement during
mixing). Further, in some embodiments, reinforcing materials (e.g.,
such a woven or non-woven scrim or mesh) may be embedded in the
unhardened geopolymer cement and/or may be adhered to a surface of
the extruded geopolymer cement (e.g., by at least partially
embedding the reinforcing materials into a surface of unhardened
geopolymer cement and/or using an appropriate bonding agent between
the reinforcing materials and the geopolymer cement). Various
additional and/or alternative implementations may equally be
utilized.
[0058] Further, consistent with some illustrative example
embodiments, a method may include shaping a geopolymer cement
(e.g., consistent with the foregoing disclosure), in an uncured
state, into a continuous and/or non-continuous, moving or
stationary, composite magnesium structural panel or panels. The
method may further include facing at least one surface of the
continuous and/or non-continuous, moving or stationary, composite
magnesium structural panel or panels with a facing material. In
some illustrative example embodiments, a method may further include
applying a reinforcing layer to, within, and/or throughout, at
least one of the continuous and/or non-continuous, moving or
stationary, composite magnesium structural panel or panels. In some
illustrative example embodiments, the reinforcing layer may, in
itself, be, by composition, similar to, and/or a composite of an
inner encapsulated higher and/or lower density geopolymer cement.
In some implementations, the reinforcing layer may be attributed to
a circumferring layer wrapping the entirety, a substantial portion,
and/or at least a portion, of the encapsulated higher and or lower
density geopolymer cement core. In some illustrative example
embodiments, the circumferring layer may, or may not, consist of
the same, and/or a similar, formulation as the inner geopolymer
cement core. In some example implementations, the circumferring
layer may be a composite of similar components, and/or may include
other additives and or components, which may be intended to impart
enhanced performance and/or economic characteristics unique to one
or more embodiments consistent with the present disclosure. For
example, in some illustrative example embodiments, unlike the
generally dense surface layers of typical gypsum wallboard and/or
gypsum building panels, a geopolymer and/or composite geopolymer
circumferring layer may not need to maintain specific density
ranges when applied to a lower density core of identical,
substantially similar, and/or generally similar, material
composition. This may offer, at least in part, a new novelty
specific to the unique capabilities existent and attainable with
the geopolymer technology disclosed herein. Additionally, in some
illustrative example embodiments, unlike some traditional magnesium
building panels, whether magnesium-based formulas incorporating
primary, secondary and or tertiary compound additives intended to
negate the widely known and widely accepted high cost of magnesium
board formulations, a geopolymer circumferring layer encapsulating
the geopolymer higher and/or lower density core may, for the first
time, provide a cement formulated building panel that may create
the unique opportunity for a magnitude of manufacturing economic
efficiency improvements, which, while yielding a composite
magnesium structural panel intended for building construction, is
now, where it was not before, a cost effective measure to
incorporate concepts disclosed herein into all standard practices
regardless of residential and or commercial methodology while
imparting both superior and unique properties and performance
characteristic of the geopolymer composite magnesium structural
panel consistent with some implementations of the present
disclosure.
[0059] Consistent with the foregoing, according to some
illustrative example embodiments, an interior and/or exterior wall
panel, or other construction panel, may be provided. The wall panel
may include a geopolymer cement sheet including a geopolymer
precursor reacted with a magnesium oxide alkali activator and water
under one or more of high speed mixing and high shear mixing. The
wall panel may further include one of a facing material and a
reinforcing layer bonded to and/or embedded into a surface of the
geopolymer cement sheet.
[0060] Consistent with some example embodiments, geopolymer cements
consistent with the present disclosure may be utilized for
producing construction products including, but not limited to
concrete roof tiles, backer boards, structural insulated panels
(SIP), exterior panels and facades, concrete blocks and bricks,
stuccos, artificial rocks, concrete structural elements, line
stripping, fire doors, interior and/or exterior wall panels, as
well as many other related construction products. In some
implementations, it may be possible to provide a construction panel
that may provide fire resistance for up to four-hours or more with
a single panel as thin as about 3/8 inch up to about 1.0 inch in
thickness. Such construction panels may provide suitable and/or
superior replacements for conventional gypsum-based panels, fiber
filled ordinary Portland cement panels, magnesium oxychloride
panels, and/or magnesium oxy-sulfate panels. Further consistent
with some embodiments, e.g., which may include density reduction,
it may be possible to provide construction products that may
exhibit high fire resistance and/or heat barrier protection at
different densities. In addition to fire resistance, in some
implementations, construction products utilizing geopolymer cements
consistent with some embodiments of the present disclosure may
additionally provide mold and/or mildew resistance.
[0061] Additionally, as generally described, in some example
embodiments, construction products may be produced from geopolymer
cements consistent with some embodiments of the present disclosure
which may include various reinforcing materials. In some such
implementations, the reinforcing materials may provide increased
flexural strength, may reduce and/or minimizing shrinkage cracking
from thermal shock of fast falling furnace temperatures, e.g., as
has been experimentally observed when removing test specimens from
an 1,850 degree F., or higher (e.g., up to 2,200 degree F. or even
higher), gas furnace and cooling down to ambient during the test
methodology of ASTM E119. In some experimental testing of
construction panels utilizing geopolymer cement consistent with
some embodiments of the present disclosure both an electric muffle
furnace as well as a propane gas generated furnace were used to
determine wall assembly performance in modified ASTM E119
specifications. It was noted in some testing that some construction
panels exhibited an interesting phenomenon seen in ceramics type
applications where the exposed surface of the magnesium oxide
activated geopolymer construction panels actually develop sintering
and/or fusing of the geopolymers under higher temperature
conditions which provided increased fire resistance by reducing
temperature transmission through the wall panel. This was observed
to keep the fire away from the other side of a wall for longer time
periods at temperatures reaching and exceeding 2,000 degrees F. The
experimentally tested panels appeared to actually act in a
refractory way, which may make them especially useful for high
temperature resistance.
[0062] Further, consistent with some example embodiments, products
(including, but not limited to construction products) utilizing
geopolymer cement consistent with some embodiments of the present
disclosure may exhibit greatly improved water resistance, mold
resistance, and/or mildew resistance, e.g., as compared to
conventional gypsum-based construction products.
[0063] Consistent with the foregoing, some illustrative example
applications in which some embodiments of geopolymer cement
consistent with the present disclosure may find beneficial use may
include, but are not limited to, any of the following:
[0064] Fire-resistant wall panels, floorboards or roof panel
systems where a fire barrier is required for desired fire ratings.
Examples of such fire-walls may include shaft liners around
elevators or fire-wall separations in commercial buildings or
apartments where a building code requires that fire or smoke cannot
be passed from one area to another area for a minimum of, e.g., 1,
2, 3, 4 or more hours.
[0065] Ballistic panels and/or walls and safe rooms. Geopolymer
cement manufactured consistent with some embodiments of the present
disclosure may result in very high compressive strengths, and when
combined with hard aggregates such as granite, may provide
excellent systems that are antiballistic and may be able to
withstand impact from bullets and/or other projectiles. Panels may
be made more flexible and/or thinner incorporating glass, metal
and/or nylon mesh that may bind tenaciously to the geopolymer
cement matrix. Walls and panels developed for this use may also be
useful in providing blast barriers for critical areas subject to
explosions such as airports, embassies, chemical plants and fuel
depots. Additionally, the use of geopolymer cements consistent with
some embodiments of the present disclosure may be used to replace
gypsum boards that are commonly used for wall boards in safe rooms,
and may, in some situations, be capable of achieving up to a 4-hour
(or more) fire rating using the ASTM E119 test, compared to only
1-hour typically observed with conventional gypsum boards in a
single 1/2'' or 5/8'' board thicknesses.
[0066] Structural and non-structural walls, roofing and flooring
and other support structures for residential and commercial
building construction including structural insulated panels (SIP),
interior and exterior wall panels, backer boards, exterior facades,
and a geopolymer matrix foam, e.g., which may replace either
polystyrene or polyurethane foam insulating materials in the center
of an SIP panel.
[0067] Concrete blocks, bricks and tiles, tile backer boards and
other precast cement elements.
[0068] Exterior and interior roof coatings and panels. The
relatively higher strength and earlier strength development
properties of some geopolymer cements and/or products consistent
with some embodiments of the present disclosure may be well suited
for use on any roofing material, including on Styrofoam insulating
panels. This may provide water, mildew, fire, bacteria and algal,
wear, abrasion and impact resistance to the roof while helping
maintain proper insulation properties and chemical resistance.
[0069] Spray coatings to impart fire resistance, mold and mildew
resistance, impact resistance and other related properties on
surfaces including, but not limited to, gypsum boards, wood, OSB
panels, asphaltic or other flammable roof shingles, plastic or any
other fire prone/combustible building facades.
[0070] Other miscellaneous applications include 3D printing, wood
roof trestles and trusses, steel and concrete beams for high-rise
buildings, and artificial rocks or boulders.
[0071] Consistent with the foregoing, geopolymer cement products
consistent with some embodiments of the present disclosure may be
used for a multitude of construction applications where increased
fire-resistance may be desired and/or required. Producing
construction panels made consistent with some embodiments of the
present disclosure may allow for wall assemblies that can provide
fire barriers for at least 2-hours, and perhaps up to 4-hours or
more, using single wall panels of 1/2'' or 5/8'' in thickness,
e.g., as compared to gypsum boards that may typically require
multiple boards to achieve anything greater than a 1-hour fire
rating. For example, if a building code requires a 4-hour fire
rating, current gypsum boards may often require a wall assembly
with four (4) Type X or Type C boards of usually 5/8'' thickness
each, and assembled together (totaling 21/2'' of total space).
Boards utilizing geopolymer cement consistent with some embodiments
of the present disclosure may accomplish the same, or better, fire
barrier protection using only one (1) board of 3/8'' or 1/2'' or
5/8'' or 3/4'' or 1.0'' in thickness, and/or any other suitable
thickness.
[0072] A variety of illustrative example embodiments have been
described, each including a variety of features, concepts,
formulations, and arrangements. It will be appreciated that
features, concepts, formulations, and arrangements disclosed in the
context of one, or several, discrete embodiments are susceptible to
application in other embodiments, and/or susceptible to combination
with features, concepts, formulations, and/or arrangements
discussed relative to multiple different embodiments. Herein, such
combination of features, concepts, formulations and arrangements
from the several embodiments is expressly intended to be within the
scope of the present disclosure.
[0073] A variety of feature, advantages, implementations, and
embodiments have been described herein. However, it will be
appreciated that the foregoing description and the depicted
embodiments are only intended for the purpose of illustration and
explanation, and should not be construed as a limitation on the
present invention. It will be appreciated that the features and
concepts associated with the various embodiments are susceptible to
combination with features and concepts of other disclosed
embodiments. Additionally, it will be appreciated that the concepts
embodied by the description and illustration are susceptible to
variation and modification, all of which are intended to be
encompassed by the present invention.
* * * * *